In general, a relay system may be used to expand a service coverage even to a shadow area which a signal from a base station is unlikely to reach during a mobile communications service due to a special topography of an area or a natural feature. An optical relay system may be referred to as an example of the relay system. The optical relay system is widely used for the reason that it serves to minimize a signal loss in a recent mobile communication service during which a relatively high-frequency signal is utilized.
The optical relay system includes a donor device and a remote device that are connected to each other via an optic medium. The donor device serves to convert an RF signal received from the base station to an optical signal thereby transmitting it to the remote device, and the remote device serves to restore the optical signal received from the donor device to the RF signal thereby emitting to a terminal. Contrary thereto, the remote device converts the RF signal received from the terminal to the optical signal thereby transmitting to the donor, and the donor device restores the optical signal received from the remote device to the RF signal thereby transmitting to the base station.
In general, the remote device of the optical relay system includes remote driving units corresponding to each of frequency bands so that it can amplify and adjust the RF signal photoelectric-converted by an optical conversion unit to transmit to the terminal or to receive from the terminal the RF signal for each frequency band. And, the remote driving units are connected in parallel to the optical conversion unit within the remote device of the optical relay system. That is, the remote driving units each receive the RF signal divided for each corresponding frequency band through a divider provided in the optical conversion unit, or the optical conversion unit and a separate divider.
As such, in the remote device of the optical relay system, when the remote driving units are arranged in parallel, there is a high possibility that original signals are damaged as the RF signals in the range of various frequency bands are processed by being divided and combined by one divider. Further, there are problems that it is difficult to design electric wiring between the optical conversion unit and the remote driving unit, there is a high probability of an erroneous connection there-between, and it is difficult to arrange, assemble and replace the remote driving units.
An object of the inventive concept is to provide a remote device of an optical relay system enabling remote driving units to be arranged in series therein, and arrangement, assembly and replacement of the remote driving units to be easier.